If you have one of a few different seaters for a 6br, 6ppc etc, can you not use that for a close estimate. I mean, lots of wiggle room with lock rings at both places for adjustability. Maybe I'm missing something here or am not sure what dimensions you're referring to. Also, when I make a wilson type inline seater for others, I use a loaded round with the bullet set about where I want it to get me close with both oal of the die as well as putting the seater stem at roughly middle of travel, etc. Hope that makes sense anyway. Hard to believe Redding called a spec that can be measured as proprietary too but it is what it is, I suppose.
I don't have a standard seater for any of my comp cartridges of I'd be glad to get you some numbers. Come to think of it though, if I can find it, I think I have a 6.5 Grendel redding seater around here and would bet the numbers are the same.
